A wide variety of drivers or switches, e.g., metal-oxide semiconductor field-effect transistors (MOSFETs), are utilized in motor vehicles to drive inductive loads, such as solenoids. In a typical application, a control signal, provided by a gate drive circuit, is applied across a gate and a source of a MOSFET to control energization of a solenoid that is coupled to a drain of the MOSFET. In modern motor vehicles, a motor vehicle chassis or frame has been electrically coupled to a negative or ground side of a battery. As such, most of the electrical loads within the vehicle have utilized the chassis as a current return path to the battery. Unfortunately, utilization of the chassis as a current return path, for multiple electrical loads, can result in potential differences along the chassis.
In most motor vehicles, one or more of the electrical loads in a motor vehicle may have one terminal tied to the battery and the other terminal tied to a drain of a MOSFET, e.g., an N-channel power double-diffused metal-oxide semiconductor (DMOS) driver, which is turned on in order to energize an associated load. As up-integration has become more prevalent, multiple of these power DMOS drivers have been integrated onto the same junction-isolated integrated circuit (IC) silicon die, along with associated gate drive circuitry, fault diagnostic circuitry and many other types of circuits, including digital logic.
A problem with this up-integrated approach occurs when an output terminal of one or more of the DMOS drivers is shorted to a negative potential, relative to the ground of the IC die (i.e., subjected to a short below ground (SBG)). This can occur, for example, due to the potential differences that exist along the chassis of the vehicle. Under this condition, circuits of the IC can malfunction with a variety of symptoms, such as adjacent drivers turning off when they should be on.
What is needed is a technique that reduces the likelihood of integrated circuit malfunction when an output terminal of a driver of an integrated circuit is taken to a negative potential.